The present invention relates to printing devices. More particularly, the present invention relates to a vacuum platen and method for use in printing devices.
Printing devices, such as inkjet printers and laser printers, use printing composition (e.g., ink or toner) to print text, graphics, images, etc. onto a print medium in a printzone of the printing device. Inkjet printers may use print cartridges, also known as xe2x80x9cpensxe2x80x9d, which shoot drops of printing composition, referred to generally herein as xe2x80x9cinkxe2x80x9d, onto a print medium such as paper, transparencies or cloth. Each pen has a printhead that includes a plurality of nozzles. Each nozzle has an orifice through which the drops are fired. To print an image, the printhead is propelled back and forth across the print medium in the printzone by, for example, a carriage while shooting drops of ink in a desired pattern as the printhead moves. The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as thermal printhead technology.
In a current thermal system, a barrier layer containing ink channels and vaporization chambers is located between an orifice plate and a substrate layer. This substrate layer typically contains linear arrays of heating elements, such as resistors, which are energized to heat ink within the vaporization chambers. Upon heating, the ink in the vaporization chamber turns into a gaseous state and forces or ejects an ink drop from an orifice associated with the energized resistor. By selectively energizing the resistors as the printhead moves across the print medium, the ink is expelled in a pattern onto the print medium to form a desired image (e.g. picture, chart and/or text).
Print media are transported through the printzone one or more times by a print media handling system of the printing device. Print media handling systems may take on a variety of different forms including those that utilize a belt or web transport that is disposed around a pair of driven rollers. Such belt or web transports may utilize a vacuum force to secure the print medium during transport through the printzone. Such vacuum force may be established through the use of a vacuum platen with which the belt or web transport is in fluid communication. Vacuum platens typically include a plurality of apertures through which an airflow is established by a vacuum source. This airflow is fluidly coupled to the belt or web transport by a plurality of apertures in the belt or web transport.
The environment in the area of the printzone is often full of printing composition aerosol and spray, as well as print medium dust and other types of debris. Over time, the apertures of a vacuum platen may fill and partially or completely clog with such debris. Such clogging reduces the airflow, thereby decreasing the securing force holding the print medium against the belt or web transport. If the print media is improperly secured to the belt or web transport while passing through the printzone, then both output print quality of the printing device and printing device throughput will likely decrease. In addition, print media with improperly printed output will be wasted.
In some cases, the apertures of a vacuum platen may fill with enough debris so that the airflow is substantially reduced or eliminated, resulting in insufficient or no securing force for holding the print medium to the belt or web transport. In such cases, the printing device effectively becomes inoperable.
Noise is another problem associated with the use of vacuum platens in printing devices. Such noise is caused by the airflow used to secure the print media to the belt or web transport as the airflow travels through the vacuum platen. The amount of this noise varies depending on the particular configuration of the vacuum platen, but it can reach objectionable levels to some users of printing devices. In such cases, depending on the extent of user noise intolerance, printing device use will decrease or, even worse, cease altogether.
Alleviation of these above-described problems would be a welcome improvement, thereby helping minimize delay in the completion of printing tasks, helping maximize printing device throughput, helping prevent instances of waste of print media, and helping quiet annoying noise created during use of the printing device. Accordingly, the present invention is directed to solving these problems.
An embodiment of a vacuum platen in accordance with the present invention for use in a printing device, having a vacuum source, includes a first surface having a plurality of first apertures therethrough and a labyrinth configured to include a plurality of passageways each of which is fluidly coupled to at least one of the first apertures. The vacuum platen also includes a second surface having a plurality of second apertures therethrough each of which is fluidly coupled to the vacuum source and at least one of the passageways thereby establishing an airflow from the first apertures, through the passageways, and out the second apertures. The vacuum platen additionally includes at least one receptacle in each of the passageways, each receptacle configured to collect debris from the airflow as it travels through the labyrinth.
The above-described embodiment of a vacuum platen in accordance with the present invention may be modified and include the following characteristics, as described below. The vacuum platen may further include an orifice restrictor plate fluidly coupled to the airflow. The orifice restrictor plate is configured to impede the airflow thereby helping limit the airflow required from the vacuum source which reduces vacuum source size and power requirements. The orifice restrictor plate is also configured to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device.
The vacuum platen may include a filter configured to collect debris from the airflow. In such cases, the filter may be configured to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device.
The passageways may be configured to decrease in size from the first surface toward the second surface.
An alternative embodiment of a vacuum platen in accordance with the present invention for use in a printing device having a vacuum source includes a first surface having a plurality of first apertures therethrough and a second surface having a plurality of second apertures therethrough each of which is fluidly coupled to the vacuum source. The vacuum platen also includes a plurality of passageways each of which is fluidly coupled to at least one of the first apertures and at least one of the second apertures thereby establishing an airflow from the first apertures, through the passageways, and out the second apertures. The passageways are configured to include a receptacle for collecting debris from the airflow as it travels through the passageways.
The above-described alternative embodiment of a vacuum platen in accordance with the present invention may be modified and include the following characteristics, as described below. The vacuum platen may further include an orifice restrictor plate fluidly coupled to the airflow. In such cases, the orifice restrictor plate is configured to impede the airflow thereby helping limit the airflow required from the vacuum source which reduces vacuum source size and power requirements. The orifice restrictor plate is also configured to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device.
The vacuum platen may further include a filter configured to collect debris from the airflow. In such cases, the filter may be configured to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device.
The passageways may be configured to be successively smaller in a direction of the airflow.
Another alternative embodiment of a vacuum platen in accordance with the present invention for use in a printing device having a vacuum source which produces an airflow and a printzone where printing composition is deposited on a print medium includes structure for distributing a vacuum hold-down force over the printzone. The vacuum platen also includes structure for conducting the airflow from the vacuum source to the structure for distributing. The vacuum platen further includes structure for collecting debris from the airflow in the structure for conducting by changing a direction of travel of the airflow as it travels through the structure for conducting.
The above-described alternative embodiment of a vacuum platen in accordance with the present invention may be modified and include the following characteristics, as described below. The vacuum platen may further include structure fluidly coupled to the structure for conducting and the vacuum source for restricting the airflow as it exits the structure for conducting thereby helping limit the airflow required from the vacuum source which reduces vacuum source size and power requirements. The structure for restricting is configured to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device.
The vacuum platen may further include structure for filtering debris from the airflow. In such cases, the structure for filtering is configured to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device.
An embodiment of a method in accordance with the present invention for use in a vacuum platen of a printing device, the printing device having a vacuum source and a printzone where printing composition is deposited on a print medium includes distributing a vacuum hold-down force over the printzone. The method also includes conducting an airflow causing the vacuum hold-down force from the printzone to the vacuum source and collecting debris from the airflow by changing a direction of travel of the airflow as it is conducted from the printzone to the vacuum source.
The above-described embodiment of a method in accordance with the present invention may be modified and include the following characteristics, as described below. The method may further include restricting the airflow before it reaches the vacuum source to impede the airflow thereby helping limit the airflow required from the vacuum source and also to reduce an acoustic energy level of the airflow thereby helping to quiet the vacuum platen during use thereof in the printing device. The method may include filtering debris from the airflow.